Locking means for screw threaded fasteners



March 29, 1938. c G, OLSON "2,112,494

LOCKING MEANS FOR SCREW THREADED FASTENERS Filed NOV. 2, 1937 Patented Mar. 29, 1938 UNITED STATES LOCKING MEANS FOR SCREW THREADED FASTENERS Carl G. Olson, Chicago, 111., assignor to Illinois Tool Works, Chicago, 111., a corporation or Illinois Application November 2, 1937, Serial No. 172,430

6 Claims.

This invention relates generally to locking devices, and more particularly to self-locking screws and nuts.

It is an object of the present invention to provide locking devices such as self-locking screws and self-locking nuts having means in association with the clamping surfaces thereof for cutting and subsequently crowding into the confines of the clamping side of such devices mate- 10 rial of the work so as to positively secure against inadvertent loosening.

More specifically, the inventiori contemplates locking devices, as set forth above, wherein the clamping side thereof is provided with a rela- 15 tively shallow indentation or pocket in operative a ssociationwith a cutting edge adaptedto cut and subsequently crowd material into said recess or pocket during the final tightening of the screw head or nut.

Another object of the presentinvention is to provide locking devices of the type referred to above, wherein a cutting edge and abutment section have in association therewith means for preventing the cutting edge from partially sev- 25 ering the work until a predetermined clamping pressure is exerted against the work.

The foregoing and numerous other objects and advantages will be more apparent from the fol lowing detailed description when considered in 30 connection with the accompanying drawing,

wherein Figure 1 is a side elevational view of a screw in which the clamping side thereof is equipped with looking sections of the type contemplated 35 herein, a portion of the screw shank being broken away; I

Figure 2 is a transverse sectional view of the screw head shown in Figure 1, said view being taken substantially along the line 2-2 of Fig- 40 ure 1;

Figure 3 is an 'enlarged fragmentary sectional view of one of the locking sections shown in Figures l and 2;

Figure 4 discloses the locking sections contem- 45 plated by the present invention in operative association with the clamping side of an internally, threaded clamping member or nut, a portion of the nut being broken away to more clearly illustrate'the structural detail of one of the 5 locking sections, the depression or indentation of said locking section differing slightly from the semi-spherical indentation shown in Figures 1 to 3, inclusive;

Figure is a view of the'underside of the 55 nut shown in Figure 4 to more clearly illustrate the semi-cylindrical cross-sectional contour of the indentations or pockets;

Figure 6 discloses the locking sections shown in Figures 1 to 4, inclusive, associated with the clamping side of a screw which is adapted to 5 form its own thread when turned within an unt'hreaded aperture of the work;

Figure '7 is a view similar to Figure 3 disclosing a locking section having a slightly modified shallow recess or indentation, the dot-and-dash 10 line indicating the manner in which the cutting edge may be rendered more acute in instances where such cutting edges are required; and

Figure 8 is a fragmentary sectional view disclosing a locking device having means in the form of protuberances associated with the locking sec tions for preventing the cutting edge of said locking sections from partially severing the work piecev until a predetermined clamping pressure has been exerted against the work.

Referring now to the drawing more in detail wherein like numerals have been employed to designate similar parts throughout the various figures, it will be seen that, for the purpose of illustrating one embodiment of the invention, I have shown in Figures 1 to 3, inclusive, a locking device or screw designated generally by the numeral ID. The screw I 0 includes a threaded shank l2 and a hexagon head l4 formed integral therewith. The usual annular clamping surface I 6 extends laterally outward from the threaded shank l2 and is adapted to be clamped against the complementary surface of a work piece (not shown). I

Spaced along the clamping side of the head 5 I4 is a plurality of locking sections, each designated generally by the numeral [8. Each of these locking sections l8 includes a locking or abutment section 20 associated with and defining a relatively shallow recess or depression 22, said 40 recess in the disclosed embodiment being substantially semi-spherical in cross-sectional contour. Each locking section l8 also includes a work shifting element 2 4 having a cutting edge 26. These cutting edges 26 serve to partially sever a section of the work piece when the nut or screw head is tightened thereagainst, and to crowd said partially severed stock into the confines of recess 22 on the clamping side thereof. By thus crowding the partially severed stock into the recess, an effective locking abutment is presented which cooperates with the'abutment section or surface 20 in securing the clamping device against inadvertent loosening.

The recess or indentation 22 disclosed in Fig- 5 which the cutting edge 26b may be rendered moreures 1 .to 3, inclusive, is substantially semi-spherical in shape. Other'shapes of indentations or recesses may be employed-for example, the semi-cylindrical recesses 22a disclosed in Figures 4 and 5. These recesses'22a are disclosed in association .with the clamping side of a nut Ilia. Elements 24:; present cutting edges 26a which, when the nutis finally tightened against the work, cause sections thereof to be partially severed and crowded into the semi-cylindrical recesses or indentations 22a and thereby secure the nut against loosening. If the nut Illa is completely tightened against a work piece, its clamping surface Ilia. will clampingly bear against the work. Each recess 22a and companion work shifting element 24a constitute a locking section which is designated generally by. the numeral Ha.

In Figure 6 a slightly modified locldng section, designated generally by the numeral H2), is shown. This locking section includes an abutment surface or section 20b defining a recess or indentation 221), slightly differing in crosssectional shape from the previously described recesses 22 and 22a. A locking section 24b presents a cutting edge 261). This cutting edge serves to partially sever and crowd material of the work into complementary confines or recesses 22b of the clamping device. The dct-and-dash line shownin Figure 6 indicates the manner in acute, if desired.

Figure 7 discloses the application of the locking sections III of Figures 1 to 3, inclusive, to the clamping side of a thread cutting screw designated generally by the numeral [00. Screws of this type are usually hardened so as to enable the cutting edge 23, extending along a slot or recess 30, to cut a complementary thread in the unthreaded aperture of a work piece. threaded shank l2c of the screw lllc, when turned within the self-formed thread, draws the clamp-' ing side of the screw head Ilc toward the work and the locking sections l8 function to secure the 'screw against loosening, as previously described in completed during a movement which is substantially not in excess of one-quarter rotation of the clamping surface. Under such circumstances there is'no danger of shearing off or fracturing the partially severed work edges crowded into the recesses. However, should the device be clamped against a work surface which is somewhat resilient or yieldable, the cutting action of the edges 26 should not take place immediately upon the engagement thereof with the work. In other words, should the edges 26 begin to cut into the work upon the initial engagement thereof with the work, the stock crowded into the recesses may be completely severed from the work due to the amount of rotation required to take up the resiliency or yieldability presented by the work.

To meet the above mentioned circumstances wherein the clamping device must be tightened against a resilient or yieldable work piece, I provide a structure, as shown in Figure 8. The. clamping device is indicated generally by the numeral "id and includes on the clamping side thereof a plurality of locking sections Rd, in between which are provided pressureresisting sections 32. These pressure resisting sections 32 are preferably provided with bent or rounded work engaging extremities 34, which will resist the clamping reaction between the device Ind and the work 36 so as to prevent the cutting edges 26d of, 10 the locking sections "id to cut into the work sur- .face until a predetermined pressureresistance has been set up when the clamping device is tightened. In other words, due to the presence of the pressure resisting elements 32, no cutting action of the edges 26d will take place until an 2.

. preciable pressure has been developed between the work and the clamping device. Thus, if the clamping device is tightened against a work surface which must yield before a firm clamping action takes'place, this initial yielding or re-' siliency will be taken up bythe pressure resisting elements 32. Continued rotation of the clamping device beyond this point will cause the elements 32, as well as the cutting edges 26d, to enter the work, and in this manner "the cutting edges 26d are rendered functionally operative. ,Suflicient rotation of the clamping device 10d will take place to insure crowding of partially severed work material into recesses 2211 in the manner described in connection with Figures 1 to 7, inclusive.

It is not necessary in all instances to employ the separate pressure resisting elements 32. Thus, for example, if the work shifting element 24 is 'conflgurated, as indicated by the dot-anddash lines of Figure 3, a blunt surface portion 38 is presented, which corresponds with the blunt portion 34 of the pressure resisting elements 32 of Figure 8. Thus cutting action of the edges 26 40 will not take place until considerable pressure has been established or built up between thework and the clamping device; that is, until the work offers rigid resistance. From the foregoing it will be apparent that the invention contemplates means associated with the cutting edges to render said edges functionally operative only after a pre-' determined clamping pressure has been built up between the clamping device and the work.

From the foregoing description it will be understood that the invention contemplates an improved locking device of the type employing cutting edges for partially severing sections of the work. In instances where it is found desirable, these cutting edges may be associated with means, such as the pressure resisting elements 32 or the blunt surfaces 38, to control the point at which the cutting action occurs, and thus preclude the possibility of shearing off a partially severed section of the work. Also, the invention contemplates directing the partially severed stock into a crowded mass within a shallow confine or recess, and thereby effectively secure the clamping device against movement.

It will be noted that, for purposes of illustration, the extent to which the work shifting or cutting elements project axially beyond the clamping surface is somewhat exaggerated in the drawing. Obviously these elements must project only a distance suflicient to cause the indentations or' recesses to receive the crowded material.

In other words, the extent to which'these elements, such as the elements 24 project beyond the clamping surface will be determined by the degree of rotation experienced by the clampingdevice during the functioning of the cutting edges. In the present embodiment this degree of rotation is substantially one-quarter turn. It will also be apparent that looking sections may be applied to both sides of a clamping device, such as nuts. Nuts equipped with looking sections on both sides facilitate the handling thereof, it being unnecessary for the user to inspect the side of the nut which is being.- applied to the work. I

While certain structural features have been illustrated and described herein,. obviously the invention is not limited to these specific structural details, but contemplates other modifications and changes without departing from the spirit and scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A- rotary fastener adapted to be clamped against the surface of a work piece, including a. rotary threaded body having a clamping surface extending laterally outward from the threaded portion thereof, and a locking section on said body including an abutment section associated with a relatively shallow recess and also including an element having a cutting edge adapted in response to rotary tightening movement experienced by the body to cause a section of the' work piece positioned laterally outward from the threaded portion of the body to be partially severed and crowded into the confines of said recess and into locking association with said abutment section whereby to prevent loosening of the fastener.

2. A rotary fastener adapted to be clamped against the surface of a work piece, including an internally threaded rotary body having a clamping surface extending laterally outward from the threaded portion thereof, and a locking section on said body including an abutment section associated with a relatively shallow recess and also 7 including anelement having a cutting edge adapted in response to rotary tightening movement experienced by the body to cause a section of the work piece positioned laterally outward from the threaded portion of the body to be partially severed and crowded into the cones of said recess and into locking association with said abutment section whereby to prevent loosening of the fastener.

3. A rotary fastener adapted to be clamped against the surface of a work piece, including a rotary threaded body having a clamping surface extending laterally outward from the threaded portion thereof, and a locking section on said body including an abutment section associated with a relatively shallow recess which increases in cross-sectional area toward said clamping surface andalso including an element having a cutting edge adapted inresponse to rotary tightening movement experienced by the body to cause a section of the work piece positioned laterally outward from the threaded portion of the body tobe partially severed and crowded into the confines of said recess and into locking association with said abutment section whereby to prevent loosening of the fastener.

4. A rotary fastener adapted to be clamped against the surface of a work piece, including a rotary threaded body having a clamping surface extending laterally outward from the threaded portion thereof, and a plurality of locking sections spaced along the clamping side of said body, each locking section including an abutment section associated with a relatively shallow rewith said abutment section whereby to prevent loosening of the fastener.

5. A rotary fastener adapted to be clamped againstthe surface of a work piece, including a rotary threaded body having a clamping surface extending laterally outward from the threaded portion thereof, a locking section on said body including an abutment section extending inwardly of said clamping surface and an element having a cutting edge adapted in response to rotary tightening movement experienced by the body to cause a section of the work piece to be partially severed and shifted into locking association with said abutment section whereby to prevent loosening of the fastener, and pressure resisting means in association with said locking section to prevent cutting action of said edge until a predetermined clamping pressure has been established.

6. A rotary fastener adapted to be clamped against the surface of a work piece, including a rotary threaded body having a clamping surface extending laterally outward from the threaded portion thereof, a locking section on said body including an abutment section extending 'in-' wardly of said clamping surface and an element having a cutting edge adapted inresponse to the rotary tightening movement experienced by the body to cause a section of the work piece to be partially severed and shifted into locking association withsaid abutment section whereby to prevent loosening of the fastener, and pressure resisting means including a protuberance extending axially beyond said clamping surface to prevent cutting action of said edge until a predetermjned clamping pressure has been established.

CARL G. OLSON. 

